Using the program

I start every program with a label. This way you can have a number
of programs in your 15c and you just select which one to run by pressing f LABELNAME (f E in this case) or GSB LABELNAME (GSB E in this case).

Let's say you would like to know what 0.15625 as a fraction is.
You type: 0.15625, GSB E
The display shows "running" and then you see first 5 and ten sec later 32.
The fraction is therefore 5/32 (numerator=5 and denominator=32). 32 remains in X (display) after the program
finished and 5 remains in Y (type key "x><y" to see it).

Note that this program shows the resulting fraction always with positive numbers. That is: both 0.15625 and -0.15625 will result in 5/32. An extra step could be
added to add the sign at the end but that would make the program longer and it's not really needed.